A prior art (RU patent No. 2,394,635, issued on Jul. 20, 2010) discloses a process for desulfurization and demercaptanization of gas based on absorption method. The gases to be purified are pressurized, and treated by two absorbing agents, first by water solution of neutral sodium salts of hydrosulfuric acid and of carbonic acid, and then by water solution of sodium hydroxide.
The same prior art describes a device for desulfurization and demercaptanization of gas as well as removal of carbon dioxide and other acidic additives, that includes two absorbers, each of them includes a storage vessel to hold absorbing agent and a pump that provides metered flow of absorbing agent into the absorber, where the second absorber, relatively to gas flow direction, contains solution of sodium hydroxide, and exhaust collecting vessels to collect exhaust absorbing agents. The absorbers are connected in a cascade; they are pressurized; the second absorber is equipped with a circulation pump; the exhaust collecting vessel of the first absorber is connected with a charging pump that is used to dump exhaust absorbing agent into isolated chambers, where as an absorbing agent in the first absorber, water and exhaust absorbing agent from the second absorber are used; additionally, the said device includes a compressor that maintains required pressure of the gas to be purified, and a separator that is connected to the said compressor, that is used to remove gas condensate and water.
Due to the disadvantages of the said prior art, the following must be admitted: low purification performance, high alkali discharge rate, generation of a high amount of toxic waste that is hard to dispose of.
A prior art (U.S. Pat. No. 4,622,212, issued on Nov. 11, 1986) describes a process of liquid-state oxidation of hydrogen sulfide to sulfur by means of chelating complexes of iron (Lo-Cat process). In the Lo-Cat process, a catalytic reactor for conversion of hydrogen sulfide into sulfur is used, and a device to regenerate the catalyst solution.
The said process features insufficient degree of desulfurization and incapability of demercaptanization that must be admitted as its disadvantages.
A prior art (U.S. Pat. No. 8,735,316, issued on May 27, 2014) describes a process of catalytic demercaptanization by converting mercaptans to disulfides. As a catalyst, the complex CuCl with monoethanol amine (MEA), acetonitrile, or with a monobasic alcohol is used. The process flows in presence of air oxygen, at a temperature of 22-140° C. The residual amount of mercaptan sulfur can be reduced to 20 ppm.
The said process is capable of purifying only liquid media, and no data is provided concerning its capability of hydrogen sulfide removal, that must be admitted as the disadvantages of the previous invention.
A prior art (RU patent No. 2,385,180 issued on Mar. 27, 2010) describes a Claus-process of obtaining sulfur from hydrogen sulfide by means of catalytic reaction of hydrogen sulfide and sulfur dioxide.
The previous invention features primary amine treatment of the, multiple stages of the process and insufficient conversion of hydrogen sulfide to sulfur, necessity of tail gas treatment, sophisticated technological equipment, and incapability of demercaptanization, all these items must be admitted as the drawbacks.
A prior art (U.S. Pat. No. 5,286,697, issued on Feb. 15, 1994) also describes an improved Claus process.
The previous invention is also incapable of demercaptanization, and it is less efficient in hydrogen sulfide conversion.
A prior art (RU patent No. 2,405,738, issued on Apr. 27, 2010) describes a means of sulfur recovery from industrial gases by means of a catalyst that contains on dehydroxylated silica gel (97.65% by mass) impregnated with ferric phosphate (III) (2.35%), that provides sulfur formation from hydrogen sulfide.
The said art features insufficient conversion of hydrogen sulfide, and catalyst production complexity, that must be admitted as drawbacks.
A prior art (RU patent No. 2,398,735, issued on Sep. 9, 2010) describes a means of gas desulfurization by oxidizing hydrogen sulfide to elemental sulfur in liquid state in presence of a catalyst, which contains a compound of a transition metal and an organic complexing agent. To oxidize hydrogen sulfide, it is proposed to use air oxygen as oxidizer; as a compound of transition metal, cupric halogenide is used, where the amount of copper in the solution is 0.015 to 0.1% by weight, and where as an organic complexing agents, one of the following is used: dimethylformamide, pyrrolidone, methylpyrrolidone, pyridine, or quinolone; the process flows in a solvent that is taken as one of the following: monobasic alcohol, polybasic alcohol, water, or their mixtures, kerosene, isooctane, gas condensate at temperature of 20-40° C.
The disadvantage of the said process is its mediocre efficiency.